Air ionizers are widely used in industry to prevent electrostatic charge build-up and to neutralize existing charges. Ionizers are also used for therapeutic purposes to produce mostly negative ions which have a beneficial effect on respiratory diseases and allergies, perform a tranquilizing function, lower bacteria, and improve reaction time.
Known industrial ionizers use radioactive materials or alternating current corona discharge to produce positive and negative air ions. Radioactive ionizers, which are relatively weak, produce equal amounts of positive and negative ions. The alternating current corona discharge ionizers produce more negative than positive ions. The common corona discharge arrangement uses a needle point or a thin wire in close proximity to a grounded surface to produce a strong electric field. Ozone and nitrus oxides are generated as undesirable by-products.
U.S. Pat. No. 3,873,835 describes a combination of an electric fan and ion-producing carbon brushes. This device produces a draft and requires a slip ring to supply the high voltage to the rotating fan. U.S. Pat. No. 3,936,698 describes a method for producing the desired ion ratio by using two independent unipolar air ionizers of opposite polarity which are alternately energized for different periods of time. This approach is complicated and requires a fan for ion distribution.
For optimum therapeutic application, the amount of unipolar air ions inhaled must be controlled. The amount of bipolar ions is not as important as the ratio of positive to negative ions. The maximum beneficial effect can be achieved by simultaneous application of bipolar air ions having a ratio of less than one and an electric field of +500 to +1000 volts per meter. Both requirements are easily achieved by the present invention.